1. Field of the Invention
This invention relates generally to acoustic horns for material handling and, more particularly, the means for attaching acoustic horns to railroad cars for augmenting bulk material flow from railroad cars.
2. Brief Description of the Prior Art
Acoustic horns have been used for a variety of purposes related to material handling. Most commonly, sonic generators or loud speakers have been used to aid in cleaning filter media. Examples of this can be found in U.S. Pat. No. 2,962,120 to Lagarias, U.S. Pat. No. 3,118,748 to Delfs, U.S. Pat. No. 3,053,031 to Vedder, et al., U.S. Pat. No. 4,201,556 to Olsson and U.S. Pat. No. 2,854,091 to Roberts, et al. Sound generators have also been used to aid in gas/particulate separation as shown in U.S. Pat. No. 3,158,455 to Lincoln and U.S. Pat. No. 3,413,781 to Abboud.
The unloading of bins or hoppers containing bulk powdered materials such as flour, cement, gypsum, kaolin and graphite have problems associated therewith which also lend themselves to the use of acoustic horns. Quite often when unloading such bulk powdered material from trucks and rail cards, the unloading is interrupted when the material compacts or bridges near the unloading nozzle and the flow of the material from the truck or rail car ceases.
Another problem faced in unloading bulk powdered materials is funneling. In this situation, a conical airspace forms above the unloading nozzle and flow of the material is reduced or may cease completely. This is typically referred to as rat-holing.
Whether the problem is bridging or funneling, the common action taken by the operator would be to beat the side of the truck or rail car with a large hammer in order to shake the material loose. This method took an obvious toll on the trucks and rail cars. Further the unloading process is considerably delayed by having first to recognize that funneling or bridging has occurred and then, having to physically shake the material loose by beating the side of the car.
Mechanical vibrators have also been used to aid in the unloading of bulk powdered materials with some success. However, the use of mechanical vibrators may result in compaction of the material or size classification of the material resulting in the blockage becoming more severe. It is important to keep the bulk powdered material fluidized such that it will flow from the truck or rail car thus reducing manhours and the total unloading time. Further, it is preferable to have the ability to re-fluidize the powdered material once the flow stops without creating an undesirable side effect such as the damage to trucks and rail cars created by hitting them with hammers and the size classification of the material which can be caused by the use of mechanical vibrators.